3-D Large Eddy Simulation for Jet Aeroacoustics

Uzun, Ali; Blaisdell, Gregory A.; Lyrintzis, Anastasios S.

doi:10.2514/6.2003-3322

Cited by 63 publications

(71 citation statements)

References 48 publications

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“…54 The spectra obtained from the previous Reynolds number 100,000 jet simulation 49 will also be included in the comparisons. Figures 29 through 31 make comparisons at the observation locations of 30…”

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confidence: 99%

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

Uzun

Lyrintzis

Blaisdell

2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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This study is focused on developing a Computational Aeroacoustics (CAA) methodology that couples the near field unsteady flow field data computed by a 3-D Large Eddy Simulation (LES) code with various integral acoustic formulations for the far field noise prediction of turbulent jets. Noise computations performed for a Reynolds number 400,000 jet using various integral acoustic results are presented and the results are compared against each other as well with an experimental jet at similar flow conditions. Our results show that the surface integral acoustics methods (Kirchhoff and Ffowcs Williams -Hawkings) give similar results to the volume integral method (Lighthill's acoustic analogy) at a much lower cost. To our best knowledge, Lighthill's acoustic analogy was applied to a reasonably high Reynolds number jet for the first time in this study. A database greater than 1 Terabytes (TB) in size was post-processed using 1160 processors in parallel on a modern supercomputing platform for this purpose.

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confidence: 99%

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

Uzun

Lyrintzis

Blaisdell

2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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“…For details regarding the numerical implementation of the Ffowcs Williams-Hawkings method, the reader is referred to Uzun. 49 The control surface starts about one jet radii downstream of the jet exit and is situated at approximately 7.5r 0 above and below the jet at the inflow boundary in the y and z directions. It extends streamwise until the near end of the physical domain at which point the cross stream extent of the control surface is approximately 30r o .…”

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Noise prediction of a subsonic turbulent round jet using the lattice-Boltzmann method

Lew

Mongeau

Lyrintzis

2010

The Journal of the Acoustical Society of America

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The lattice-Boltzmann method ͑LBM͒ was used to study the far-field noise generated from a Mach, M j = 0.4, unheated turbulent axisymmetric jet. A commercial code based on the LBM kernel was used to simulate the turbulent flow exhausting from a pipe which is 10 jet radii in length. Near-field flow results such as jet centerline velocity decay rates and turbulence intensities were in agreement with experimental results and results from comparable LES studies. The predicted far field sound pressure levels were within 2 dB from published experimental results. Weak unphysical tones were present at high frequency in the computed radiated sound pressure spectra. These tones are believed to be due to spurious sound wave reflections at boundaries between regions of varying voxel resolution. These "VR tones" did not appear to bias the underlying broadband noise spectrum, and they did not affect the overall levels significantly. The LBM appears to be a viable approach, comparable in accuracy to large eddy simulations, for the problem considered. The main advantages of this approach over Navier-Stokes based finite difference schemes may be a reduced computational cost, ease of including the nozzle in the computational domain, and ease of investigating nozzles with complex shapes.

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“…For the direct numerical simulation of jet flows, sponge layers are widely used (see for example [20,21]). They offer the possibility to dump outgoing waves, thus reducing significantly unphysical reflections, by using a second-order filter [22].…”

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confidence: 99%

Strategy for spatial simulation of co‐rotating vortices

Deniau

Nybelen

2008

Numerical Methods in Fluids

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SUMMARYThe present numerical study is motivated by the challenge to simulate the three-dimensional spatial dynamics of a co-rotating vortex system, through the development of an elliptic instability (C. R. Phys. 2005; 6(4-5):431-450) using a high-order solver of the compressible Navier-Stokes equations. This phenomenon was studied previously only by temporal simulations. The interest of spatial simulation is first to analyse the effect of the axial velocity on the merging process, which are neglected with the temporal approach, and to study interaction with jet flows. The numerical problem is the choice of boundary conditions (BCs): for the inflow and outflow conditions as well as for the lateral BCs to represent a fluid at rest. Special attention will be paid to the latter because the difficulties come from the non-zero circulation of the vortex system considered. The classic BCs of Poinsot and Lele (J. Comput. Phys. 1992; 101: 104-129) based on the characteristics wave approach have been modified to be more adapted to the physics considered here. This new BC is based on the assumption of an irrotational flow close to the borders (in order to determine the magnitude of the waves), as the vorticity field is concentrated on the computational domain centre where the vortex system is initially placed. After a validation of these improved BCs and of all numerical tools used such as selective artificial dissipation, two spatial simulations of the vortex breakdown phenomenon have allowed validating our solver for a three-dimensional case by comparison with the results of Ruith et al. (J. Fluid Mech. 2003; 486:331-378). Thus, the merging process of equal co-rotating vortices through the development of elliptic instability with axial velocity were simulated. Three vortex flow configurations were considered with different vortex systems and velocity peaks ratio (azimuthal and axial velocities).A numerical tool has been elaborated and validated for the simulation of spatial instability development in vortex flows. The first results show this ability, and the influence of the axial velocity on the dynamics of the instabilities. However, spatial simulations are limited by the computational resources (linked to the resolution and axial domain length to capture the merging process) and restricted to academic vortex flow configuration.

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3-D Large Eddy Simulation for Jet Aeroacoustics

Cited by 63 publications

References 48 publications

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

Noise prediction of a subsonic turbulent round jet using the lattice-Boltzmann method

Strategy for spatial simulation of co‐rotating vortices

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